"Two features common to diverse sick excitable cells are “leaky” Nav channels and bleb damage-damaged membranes. The bleb damage, we have argued, causes a channel kinetics based “leakiness.” Recombinant (node of Ranvier type) Nav1.6 channels voltage-clamped in mechanically-blebbed cell-attached patches undergo a damage intensity dependent kinetic change. Specifically, they experience a coupled hyperpolarizing (left) shift of the activation and inactivation processes. The biophysical observations on Nav1.6 currents formed the basis of Nav-Coupled Left Shift (Nav-CLS) theory. Node of Ranvier excitability can be modeled with Nav-CLS imposed at varying LS intensities and with varying fractions of total nodal membrane affected. Mild damage from which sick excitable cells might recover is of most interest pathologically. Accordingly, Na+/K+ ATPase (pump) activity was included in the modeling. As we described more fully in our other recent reviews, Nav-CLS in nodes with pumps proves sufficient to predict many of the pathological excitability phenomena reported for sick excitable cells. ..."
Model Type: Neuron or other electrically excitable cell
Currents: I K; I Na,t; I Sodium; Na/K pump
Genes: Nav1.6 SCN8A
Model Concept(s): Ion Channel Kinetics; Tutorial/Teaching
Simulation Environment: NEURON; Python
Implementer(s): Barlow, Benjamin Stephen [BBarlow at uottawa.ca]
References:
Joos B, Barlow BM, Morris CE. (2018). Calculating the Consequences of Left-Shifted Nav Channel Activity in Sick Excitable Cells. Handbook of experimental pharmacology. 246 [PubMed]